i can say that the bucking or glitch as i call them lol could be something with the traction control/abs problem, had an 01 impala doing some "fluttering" ended up being wheel bearing abs sensor. the egr is also a concern as there are solenoids and they open as such and can cause a change in rpm etc... i assume its a 97-03 gtp or 04+gtp or 06+gt? change egr, change right front wheel bearing. let us know how it turns out